Radiographic Outcomes and Complications after L4 or L5 Pedicle Subtraction Osteotomy for Fixed Sagittal Malalignment in 102 Adult Spinal Deformity Patients with a Minimum 2-Year Follow-Up

The objective of this retrospective study was to provide the radiographic outcomes and complications for pedicle subtraction osteotomy (PSO) performed at the low lumbar spine, i.e., L4 or L5 for ASD patients with fixed sagittal malalignment. ASD patients who underwent L4 or L5 PSO with a minimum 2-year follow-up were included. Preoperative and postoperative radiographs, and complications were collected. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), thoracic kyphosis (TK), sagittal vertical axis (SVA), spinal lordosis (SL) ratio and global tilt (GT) on standing long-cassette radiographs. A total of 102 patients from 2 spinal centers were analyzed. 66 patients underwent PSO at L4 and 36 patients at L5. From preoperatively to the final follow-up, significant improvements occurred in LL (from − 31° to − 52°), SVA (from 13 to 5 cm), and GT (from 44° to 27°) (all, p < 0.05). 12 patients had transient neurological deficits, and 8 patients had persistent neurological deficit. 23 patients underwent revision for PJK (2), pseudarthrosis (10), neurological deficit (2), epidural hematoma (1), or deep surgical site infection (8). No PJK was observed in any of the patients with L5 PSO. PSO at the level of L4 or L5 remains a challenging technique but with an acceptable rate of complications and revisions. It enables correction of fixed sagittal malalignment in ASD patients with a globally satisfactory outcome. In comparison with L4 PSO, L5 PSO patients did not show PJK as a mechanical complication. Distal lumbar PSO at the level of L5 may represent one of the factors that may help preventing the proximal junctional kyphosis complication.